This application claims the priority of German patent document 101 36 981.6, filed 30 Jul. 2001 (PCT International Application No. PCT/EP02/07142, filed 28 Jun. 2002), the disclosure of which is expressly incorporated by reference herein.
The invention relates to a method and apparatus for detecting, evaluating and identifying a stationary or moving object, such as a vehicle.
In order to record movement profiles or states of an object, for example a vehicle, associated operational signals of the vehicle, such as on/off signals from the starter and actual speed of the tachometer, are conventionally recorded and monitored. A disadvantage of this technique is that only vehicle-related signals are recorded and monitored. Other systems are known for taking the environment of the vehicle into account, for example a millimeter-wave radar for identifying road conditions ahead from DE 199 32 094 A1, and a CW radar system (CW=continuous wave) for measuring distances and relative speeds between a vehicle and one or more obstacles from DE 199 22 411 A1. These do not make it possible for signals which are caused by the vehicle itself, and which affect the environment, to be taken into account and evaluated. Furthermore, a radar system is particularly demanding and cost-intensive in terms of installation and maintenance, and requires precise and very time- and cost-intensive adjustment.
U.S. Pat. No. 5,619,616 discloses a system for classifying automobiles based on their sound emission.
U.S. Pat. No. 5,319,611 describes an autonomous vehicle that detects obstacles in the area via sound waves reflected by the obstacles.
One object of the invention is to provide a method and apparatus for the detecting, evaluating and identifying a stationary or moving object, which is improved and simplified compared with the prior art.
This and other objects and advantages are achieved by the method and apparatus according to the invention, in which acoustic signals emitted by the object or reflected by another object or by a plurality of objects are recorded as a reference signal. Based on these signals, a relevant object, such as a vehicle that is either stationary or moving, can be detected, evaluated and/or identified acoustically with the aid of noises received from it and/or extraneous noises, including an evaluation of its own movement profile in relation to one or more coordinate axes (x, y axes), in the manner of self-localization based on sound waves. Both structure-borne and air-borne sound signals are expediently recorded as the acoustic signals.
For particularly fast, reliable and realistic analysis and evaluation of the relevant object, the acoustic signals are processed in real time and/or transmitted to other systems, such as a control and/or regulating system. In this way, it is possible to form a very early conclusion about the relevant object (in particular, its movement state and/or movement profile), so that it is in turn possible to determine information which may be necessary and/or to make decisions which are transmitted to relevant communication systems and/or control and/or regulating systems.
Advantageously, the noise signals representing the relevant or particular object are filtered out of the recorded acoustic signals. Depending on the type of object and the situation, on the one hand the filtered-out (and therefore object-related) noise signals may be processed and used for analyses. On the other hand, non-object-related acoustic signals may be processed, analyzed and evaluated from the difference between recorded acoustic signals and object-related noise signals. In this way, besides self-localization, it is also possible to detect interference affecting the object, and/or another stationary and/or moving object.
Preferably, a movement state or profile pertaining to the relevant object is calculated and/or forecast based on the recorded acoustic signals. For example, acoustic signals reflected by a guardrail of a road lane, in particular reflected noise signals from the actual vehicle, are used to determine the distance from the reflecting surface (i.e., the distance from the guardrail). In this way, taking other parameters into account, it is possible to detect, analyze and evaluate the fact that the object (i.e., the vehicle), is approaching another object (the guardrail). For example, when the lateral distance from the guardrail falls below a limit, it is possible to conclude that a driver of the vehicle is falling asleep and to deliver a corresponding warning message.
More preferably, the movement profile of the object may be calculated with respect to one or more coordinate axes. In addition or alternatively, the calculation of the movement profile may be refined using a noise analysis. For example, the object is monitored in relation to movements in the y and/or x directions with the aid of the recorded acoustic signals or noise signals. In particular, the movement profile of the object is monitored for a possible collision with the aid of the noise analysis, and when a collision risk is identified, information or a control signal is delivered to a control or regulating system. This provides a particularly straightforward active safety method for a moving object. Active accident prevention is ensured by informing and warning of possible collisions with another object.
In another advantageous embodiment of the method, information from a geographical information system, for example a navigation system, and/or from a previous noise analysis, is taken into account during the detection, evaluation and/or identification of the relevant object. This allows rapid prediction of the vehicle's own movement profile while taking into account the acoustic signals currently being recorded.
Depending on the type and embodiment, an associated priority is specified for an operator of the object, (e.g., a driver). For example, an identification and self-localization can thereby be adjusted in stages by the driver. Alternatively, or in addition, an operation with a higher priority is given precedence over an operation with a lower priority, ensuring that, for example, the driver is given higher authority than a passenger, or that safety-relevant operating steps of the proposed system are given higher authority than comfort-relevant operating steps which the driver can carry out.
Advantageously, acoustic signals, noise signals and/or other operational signals from neighboring objects and/or systems are recorded, received and/or taken into account during a relevant analysis. Such cross-referencing of a plurality of objects in a pre-determinable region (for example inside a traffic network) makes it possible to identify the traffic flow currently existing in this traffic network. With the aid of the identified traffic flow, for example, the relevant object can be navigated by corresponding signal interchange with the aid of the navigation system.
For high speed and maximum realism, the recorded acoustic signals or noise signals are processed with the aid of at least one analysis, by assigning signal patterns using neural networks and/or fuzzy logic. As an alternative or in addition, the recorded acoustic signals and/or noise signals may be compared, identified and evaluated with the aid of signal patterns stored in a table.
The invention also provides a device for detecting, evaluating and identifying a stationary and/or moving object such as a vehicle, with at least one sonic transducer system comprising a plurality of electroacoustic, electromechanical and/or mechanical transducers. The sonic transducer system has a predeterminable directional characteristic for recording acoustic signals emitted by the object or reflected by another object or by a plurality of objects. The device also includes an evaluation unit for detecting, evaluating and/or identifying the object with the aid of the recorded acoustic signals.
The sonic transducer system comprises, at least one sound or noise sensor (in particular a direction-sensitive sound sensor). The transducer is advantageously designed as a microphone with a spherical and/or lobe characteristic. In this case, the sonic transducer system and the evaluation unit preferably form a passive acoustic radar based on sound waves. Such a passive acoustic radar method allows particularly straightforward and fast processing of the recorded acoustic signals compared with a conventional active radar method.
For multidirectional recording of the acoustic signals or object-related noise signals, the object comprises a plurality of sound sensors. These are, for example, arranged at different places in the vehicle with different orientations, permitting direction-related self-localization of the vehicle. (For example, the direction is used in a driver assistance system.) Depending on the type and embodiment of the device (referred to below in brief as an acoustic radar) a plurality of sound sensors are combined to form a group.
For extensive recording or positioning of the object, the object-related transducer or transducers arranged in an environment have a communication link to a control center. The use of such a network of object-related noise sensors, and noise sensors arranged stationary in the environment, allows analysis of the traffic flow using the control center. To this end, the device is expediently integrated in a traffic monitoring system.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.